What'll they think of next? A protein from E Coli to alter Neural Progenitors Stem Cells by design into Specific Types of Neurons:
As the recipe book for turning stem cells into other types of cells keeps growing larger, the search for the perfect, therapeutically relevant blend of differentiation factors is revealing some interesting biology.
This new research reports the possibility that a protein from E. coli bacteria combined with small molecules can act synergistically to push pluripotent cells into functional neurons.
It seems that when it does the pushing will very much determine what sort of neuron we will that is pushed on stage
Pluripotent stem cells (PSCs) possess two important properties, including indefinite self-renewal and the ability to differentiate into most cell types
In all the tissues of our body, these pluripotent cells go down a well defined sequence of stages whereby they grow in number and various differentiations take place. Just when and how long each differentatied stage is allowed to last determines what sort of cell will emerge.
In the brain for example, at the simplest level all neurons and astrocytes emerge from a common pluripotent cell, and some of the astroctye progenitors seem to brancn off and form oligodendroctyes. And these each of those types develops still more different features from others of its class.
Accumulating evidence suggests that maintenance of pluripotency and differentiation into lineage-committed progenitors of PSCs are tightly regulated by the interplay of a few transcription factors termed master stemness regulators
As they go further down the road to those target destinations further key differentiations occur in sequence. and various of hese cells can become further kinds within that genus of cell. Until?
Until the cell type that they have become is called for by the brain and told to go "on stage" Before that they are held in a "pool" in a neurogenic niche "not yet ready for prime time"
These unique features of Pluripotent stem cells make them invaluable tools not only for exploitation as therapeutic agents in regenerative medicine but also for elucidation of the molecular mechanisms regulating proliferation and differentiation of stem cells
Much of what goes wrong in this long process from pluripotent cells to final "players" is due to the pushing of some of these cells either too soon or too late into their functioning roles.
In the case of skin tissue, we can get either insufficient wound healing or on the other hand, hypertrophic scarring, if the right time for coming on stage is not worked out by this complex system of which they speak
Here the possibility is raised that an Ecoli protein can be used to allow treating physicians to choose the desired time the release of a neurogenesis differentiation factor to either bring just the right actor on stage or perhaps prevent the wrong actor from going on.
The authors say that the differentiation of pluripotent stem cells can be conceived as two simple steps: first, a stem cell decides to no longer be a stem cell and begins to differentiate; second, the cell decides what kind of cell it wants to be.
"Although there has been considerable research in this field, there is still a bottleneck in being able to produce a high number of stem cells efficiently,"
Sox2 is a key player in the maintenance of pluripotency and stemness, and thus inhibition of its function would abrogate the stemness of pluripotent cells and induce differentiation into several types of cells
Here is striking new strategy that relies on a combination of Sox2 inhibition with lineage-specific induction to promote efficient and selective differentiation of pluripotent P19 cells into neurons.
The research began when Sungkyunkwan University scientists in Korea made a serendipitous discovery that Sox2—one of the four Yamanaka factors that affect a stem cell's ability to remain a stem cell or differentiate—can bind to a bacterial chaperone protein, Skp. A chaperone protein does very much that: it binds to a potentially active protein not allowing it to react until a later time.
They then tested what would happen if Skp was introduced into stem cells and found that it could initiate differentiation.
This led to the hypothesis that Skp could be combined with other techniques to make differentiation more efficient.
When P19 cells transduced with Skp protein, an inhibitor of Sox2, are incubated with a neurogenesis inducer, the cells are selectively converted into neurons that generate depolarization-induced sodium currents and action potentials
These authors developed a protocol to induce neuron differentiation, where the bacterial protein Skp acts in the first step by binding to Sox2 and inhibiting its function.
The small chemicals neurodazine (Nz) and neurodazole (Nzl) then act in the second step by telling the stem cell to become a neuron.
By influencing both steps, more functional neurons can be produced per batch of stem cells and at a faster rate if using either protein or small molecules alone. We are essentially deciding what happens within the 'womb" within each tissue where the pluripotent cells are produced, nurtured, differentiated one way or another, and then mobilized on stage to properly "born"
"The synergy thus mainly arises from combining suppression of stemness by protein and directing lineage-specific commitment by chemical inducers
Signaling pathway studies lead us to conclude that a combination of Skp with the neurogenesis inducer enhances neurogenesis in P19 cells by activating Wnt and Notch pathways. The present differentiation protocol could be valuable to selectively generate functionally active neurons from pluripotent cells.
One weakness, of course, of the protocol is that there are safety concerns around using bacterial proteins such as Skp in a therapeutic setting.
However, using this protein is advantageous compared to introducing genetic elements because protein cannot cause any genetic alteration or instability, which are the major concerns of using virus-mediated gene delivery to the stem cells.
The authors hope that this study can encourage others to develop similar approaches based on small molecule mimics of the first stage of stemness suppression.
Combining Suppression of Stemness with Lineage-Specific Induction Leads to Conversion of Pluripotent Cells into Functional Neurons
Shin says. "Hence this process stands as an example of rationally designed cell differentiation to achieve a high level of lineage commitment efficiency."
They are now working on using similar combinatorial approaches to explore how to make differentiation more efficient in other cell types, particularly those in the heart.
